How do you like the Tamron overall? Are you happy with the optics? I'm still using a Canon EOS 300D (Rebel, Kiss Digital) but planning on moving to the EOS 90D soon. The R family is just too pricey for my use cases and I still don't like EVF. The 90D is weather sealed so I want to pair it with weather sealed lenses and have been looking at some Tamron, Sigma, and Tokina lenses. Canon L series are just crazy expensive. :/
Honestly, even though the 70/80/90D are great ASP-C cameras with a good weather-sealed body going back to the 1970s, I would either move to the Canon 6D II full-frame and focus on EF glass as it retains its value much more, aside from third-party (Sigma Art, etc.) for ASP-C at comparable prices or the R6 (comparable build with the 6D II) and get premiere quality glass with the L lineup.
I am so fearful over weather-sealed as I shoot outdoors in high humidity and downpours that I can't fathom losing a $700 lens (let alone a $2000-3000 body) in a 2-minute dribble of rain that I have two Tamron's that'll I'll keep (alongside a Canon 24-105 F4L): The Tamron 70-200 G2 and the SP35mm 1.8 for astrophotography (but looking into Irix Blackstone 15mm f/2.4 [that registers as 2.8]) for the build quality as well as the wide-angle to give me more long shots without star trail (Milky Way season is coming up and all that extra light will drastically improve if following either the 500 or 200 rule at 15mm).
The 70-90D cameras are tough bodies, but you're limited in a lot of aspects. I would trade it in and go with the 6D II myself to take the first step. Come November (Black Friday), I'm sure the $1200 price-tag will be reduced to $1000-1100 which is comparable to a 90D.
As far as optics go, Tamron is pretty decent when compared to first-party releases, at 1/2-1/3rd the price (used in AA/AB [and even C if you don't mind minor scratches on the body, not effecting the optics whatsoever] quality). With a little post-edit tweaking, I don't think many could tell I shot on a Tamron 70-200 over a Canon 70-200 when you fiddle with it.
The EFV is pretty good in the R5 when compared to the 2 million pixels in the R6 and mirrorless M50. The articulating screen will help a lot more with angled shots than using the EFV. That said, the R5 is I believe 5 million pixels while the "rival" to the R5 will have 9 million on Sony's A7IIIs.
And while the L's are expensive, look back on history dating to the 1980s with manual focus. They are insanely expensive with the technical aspects because the glass is just so incredible (too bad they discontinued the Canon 50mm f/1 [I believe]) as that has more value than a newer f/1.2. Take the L over the comparable 24-105 that isn't weather-sealed at $400~ and you'll regret not even getting a $500 used F4L in "bad shape".
PS: My backup camera is a Canon T6i (Kiss x8i). While it's good in the light, the ISO is horrible if you need to bump it up (even at f/1.8) and you get swiss cheese at like 3200-6400 whereas I can bump up to 20000 on a 5D without issue.
I'm more of a hobbyist photographer, but, I like to have pro gear that can stand up to the elements. I feel safe taking it down a river trek in the middle of a downpour to capture waterfalls, etc. and a 10-minute wipedown plus throwing it in a dry box (on my purchase list) will ensure that it'll last the 6-years in release cycles.
But yeah, completely agree. Photography is expensive and you have to decide on what type of shooting you want to do and not really lean towards a multipurpose lens like the 24-105 F4L as the 24-70 is much sharper and the 70-200 picks up with that sharpness.
These are just my opinions though.
Consolidate your gear to trade up and go with the 6D II if the $2400 price tag of the R6 is too much and a fine prime (or general-purpose lens) of high caliber and enjoy yourself without limitations (look at the sensors on them, etc.